your site made it really easy for me to install 1/2 a dozen old versions of your theme. thanks for that too.
You are welcome! There are some releases prior to 2.0 that are not 100% correct since back then I didn't plan to track all the versions and I messed with some files
Dropping back to AF2 & disabling the shader gets it to run fine on those machines. all 3 machines are new / fast W10 PCs & have 4k screens. not sure why 1 would run any diff than the other. the laptop is ridiculously fast but the 2 PCs certainly aren't dogs. Both are newer i7s w/ a ton of ram & decent vid cards.
It seems the issue here is with OpenGL shaders, I've had some issues in the past with my test rig: a xeon workstation with fast SSD, 32 GB of ram and Quadro card. I had to implement some tricks to make the layout smoother, but then I discovered a setting in nVidia control panel that made all my layouts run at 60fps with no tricks needed, which was the expected behavior of such a "monster" rig.
Maybe there's an nVidia card on your PCs? Another issue could be the high resolution, you can try reducing the resolution in Arcadeflow options, there's a field where you can put WIDTHxHEIGHT, just try something radical like 640x400 or similar to see if it improves.
I'll check the setting of my Quadro card tomorrow and report back